An internal combustion engine for motor vehicle purposes and the like is typically designed with the carburetor in a central location on the engine in relation to the cylinders. At low engine speeds, all of the cylinders receive equal amounts of the air-fuel mixture from the carburetor by way of the intake manifold system. At higher engine speeds, however, cylinders closer to the carburetor receive larger amounts of the air-fuel mixture than do cylinders farther from the carburetor. Accordingly, it is desirable to equalize the amounts of air-fuel mixture supplied to the cylinders at higher engine speeds in order to improve the efficiency of the engine.
A related matter is that, when the engine is used to power a vehicle, the engine generally operates under a heavy load only when the vehicle is accelerating or climbing an incline. The rest of the time, the engine operates under a reduced load which, in general, is significantly lower than its maximum power output. Accordingly, an engine used to power an automobile generally operates at less than maximum fuel efficiency a major portion of the time.
Various attempts have been made to solve the foregoing problems, typically through a cylinder disablement scheme in which the fuel efficiency is improved by selectively shutting off the air-fuel supply to several cylinders during periods of time when a reduced power output will adequately operate the vehicle. The air-fuel supply to the cylinders is restored when the engine is operated under a heavy load.
These prior attempts to improve fuel efficiency have generally accomplished their intended purposes, but they have not been satisfactory in all respects. Typically, a single valve is provided in the manifold or the carburetor which disables an entire group of cylinders simultaneously, rather than independently controlling the air-fuel mixture for each of the cylinders. Accordingly, such devices are usually incapable of equalizing the amounts of air-fuel mixture received by cylinders near the carburetor with respect to cylinders farther from the carburetor because grouping is dictated by the ignition sequence rather than cylinder location. Further, the shut-off valves in these known systems are typically operated by a solenoid or an equivalent device, such that the valve is either completely opened or completely closed and cannot be set to one of several intermediate positions in order more precisely to regulate the flow of the air-fuel mixture.
A more serious problem with the known devices is the fact that they typically have major structural differences with respect to conventional automobile engines. Specifically, a special carburetor and/or intake manifold is generally required, and sometimes even the engine block and/or cylinder head must be significantly modified. As a result, many of the prior solutions to the problems described above either cannot be incorporated into the existing engines of vehicles which have already been manufactured or else they can be incorporated into such engines only through major and expensive modifications of the conventional components of the engine or through the substitution of expensive new components.
It is therefore an object of this invention to provide an apparatus for regulating the quantities of the air-fuel mixture supplied to the cylinders of an internal combustion engine in which the air-fuel mixture supplied to each of the cylinders can be regulated independently, whereby the flow of the air-fuel mixture to a selected number of cylinders can be completely shut off.
It is a further object of the invention to provide an apparatus, as aforesaid, in which the mechanism regulating the flow of the air-fuel mixture to each cylinder is adjustable to an infinite number of settings.
It is a further object of the invention to provide an apparatus, as aforesaid, which is simple, inexpensive and durable.
It is a further object of the invention to provide an apparatus, as aforesaid, which is easy to install in an existing vehicle engine and which requires little or no modification of the conventional components of the engine.